US5082998A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Switching power supply for microwave oven
Assignee: Yutaka Electric Mfg Co Ltd
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Filing: 1990-10-31
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Granted: 1992-01-21
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Expires: 2010-10-31
Abstract
Abstract The present invention relates to a switching power supply for a microwave oven in which a DC power is changed to a pulse by means of a switching element coupled to a primary winding of an inverter transformer to supply the power to a high frequency oscillator (hereinafter referred to as the magnetron) coupled to a secondary winding. The inverter transformer has a supplementary winding which is coupled to control side of the switching element to form a self-excited voltate resonance type. As to the self-excited type, a switching frequency is changed by itself relative to the change of the input voltage and output power for stabilizing the output, thereby realizing same level of operation as a power switching circuit compulsory excited from outside control circuit (hereinafter referred to as The Outside-excited type).
Inventors
- 👤 Hitoshi Yoshioka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 04:25
CPC Classifications
H; H05; H05B; H05B6/00; H05B6/64; H05B6/66; H05B6/68; H05B6/681; H05B6/682; H05B6/685
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
228 words
A switching power supply for a microwave oven including a switching means for changing power from a DC source to a pulsed form, said switching means coupled to a primary minding of an inverter transformer supplying power to a magnetron, the magnetron coupled to a secondary winding of said inverter transformer, said switching means including a control input and said inverter transformer including a supplementary winding coupled to said control input of said switching means thereby providing a self-excited voltage resonance power source, wherein said switching means comprises a primary transistor having a base, an emitter and a collector, the collector being connected in a series connection with said inverter transformer and said supplementary winding being connected between the base and the emitter through a diode, further comprising reference means for generating a reference voltage by dividing an input voltage, comparator means, said reference means inputting said reference voltage to one terminal of said comparator means, a voltage detected by a resistor coupled to the emitter of said primary transistor being connected to another terminal of said comparator means, further comprising a supplementary transistor connected between the base and emitter of said primary transistor, an output of said comparator means connected to said supplementary transistor for turning on said supplementary transistor at a time when said detected voltage exceeds said reference voltage, thereby turning off said primary transistor.
Claim 2
Dependent Claim
228 words
A switching power supply for a microwave oven including a switching means for changing power from a DC source to a pulsed form, said switching means coupled to a primary minding of an inverter transformer supplying power to a magnetron, the magnetron coupled to a secondary winding of said inverter transformer, said switching means including a control input and said inverter transformer including a supplementary winding coupled to said control input of said switching means thereby providing a self-excited voltage resonance power source, wherein said switching means comprises a primary transistor having a base, an emitter and a collector, the collector being connected in a series connection with said inverter transformer and said supplementary winding being connected between the base and the emitter through a diode, further comprising reference means for generating a reference voltage by dividing an input voltage, comparator means, said reference means inputting said reference voltage to one terminal of said comparator means, a voltage detected by a resistor coupled to the emitter of said primary transistor being connected to another terminal of said comparator means, further comprising a supplementary transistor connected between the base and emitter of said primary transistor, an output of said comparator means connected to said supplementary transistor for turning on said supplementary transistor at a time when said detected voltage exceeds said reference voltage, thereby turning off said primary transistor.
Claim 3
Dependent Claim
228 words
A switching power supply for a microwave oven including a switching means for changing power from a DC source to a pulsed form, said switching means coupled to a primary winding of an inverter transformer supplying power to a magnetron, the magnetron coupled to a secondary winding of said inverter transformer, said switching means including a control input and said inverter transformer including a supplementary winding coupled to said control input of said switching means thereby providing a self-excited voltage resonance power source, wherein said switching means comprises a primary transistor having a base, an emitter and a collector, the collector being connected in a series connection with said inverter transformer and said supplementary winding being connected between the base and the emitter through a diode, further comprising reference means for generating a reference voltage by dividing an input voltage, comparator means, said reference means inputting said reference voltage to one terminal of said comparator means, a detected voltage representing current flowing in the primary winding of said inverter transformer being connected to another terminal of said comparator means, further comprising a supplementary transistor connected between the base and emitter of said primary transistor, an output of said comparator means connected to said supplementary transistor for turning on said supplementary transistor at a time when said detected voltage exceeds said reference voltage, thereby turning off said primary transistor.
Claim 4
Dependent Claim
228 words
A switching power supply for a microwave oven including a switching means for changing power from a DC source to a pulsed form, said switching means coupled to a primary winding of an inverter transformer supplying power to a magnetron, the magnetron coupled to a secondary winding of said inverter transformer, said switching means including a control input and said inverter transformer including a supplementary winding coupled to said control input of said switching means thereby providing a self-excited voltage resonance power source, wherein said switching means comprises a primary transistor having a base, an emitter and a collector, the collector being connected in a series connection with said inverter transformer and said supplementary winding being connected between the base and the emitter through a diode, further comprising reference means for generating a reference voltage by dividing an input voltage, comparator means, said reference means inputting said reference voltage to one terminal of said comparator means, a detected voltage representing current flowing in the primary winding of said inverter transformer being connected to another terminal of said comparator means, further comprising a supplementary transistor connected between the base and emitter of said primary transistor, an output of said comparator means connected to said supplementary transistor for turning on said supplementary transistor at a time when said detected voltage exceeds said reference voltage, thereby turning off said primary transistor.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-01-20 | 1995-07-22 | 1996-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-01-20 | 1999-07-22 | 2000-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-01-20 | 2003-07-22 | 2004-01-21 | $7700.00 | Window Closed / Lapsed |